Glass fiber reinforced elastomers

ABSTRACT

Glass fibers for use in glass fiber-reinforced elastomeric materials and method for preparing same wherein a glass fiber bundle is first impregnated with an elastomer or resinous polymer and then is coated with an elastomer compatible material to form an impregnated glass fiber bundle having an inner coating comprising an elastomer or resinous polymer and an outer coating of the elastomer compatible material.

United States Patent Marzocchi 14 1 Apr. 25, 1972 54] GLASS FIBERREINFORCED 3,413,186 11/1968 Marzocchi ..117/72 x ELASTOMERS 1,933,40110 1933 Ward ..118/427 x I 3,244,545 4/1966 Marzocchi et a1. ..1 17/1 15X [72] Alfred Mamcch" Cumberland R1 3,367,793 2/1968 Atwell ..117/126 GB[73] Assignee: Owens-Corning Fiberglas Corporation PrimaryExaminerWilliam D. Martin [22] Flled' 1970 Assistant Examiner-D. Cohen[21] App]. No.: 32,974 Att0rneyStaelin & Overman and Herman I. Hersh 52us. c1 ..1l7/65.2, 117/72, 117/115, [571 ABSTRACT 1 17/ 126 GB, 118/427, 1 18/DIG- 1 Glass fibers for use in glass fiber-reinforcedelastomeric [51-] Int. Cl ..C03c 25/02 materials and method forpreparing Same wherein a glass fib [58] Field of Search ..117/72,65.2,115, 126 GB; bundle is first impregnated with an elastomer or resinous118/427 18 polymer and then is coated with an elastomer compatiblematerial to form an impregnated glass fiber bundle having an [56]References Cited inner coating comprising an elastomer or resinouspolymer UNITED STATES PATENTS and an outer coating of the elastomercompatible material.

3,546,000 12/1970 Medney ..1 17/115 X 10 Claims, 4 Drawing Figures Patented April 25, 1972 3,658,571

5 Mg wfl wm 7 Clil'ys CLASS FIBER REINFORCED ELASTOMERS This inventionrelates to elastomeric products reinforced or otherwise combined withglass fibers and it relates more particularly to the method andcompositions employed in the treatment of the glass fibers to enhancethebondingrelationship between the glass fibers and the elastomericmaterials for making fuller utilization of the desirable characteristicsof the glass fibers in their combination with the elastomeric materials.

The term glass fibers, as used herein, shall refer to (1) continuousfibers formed by the rapid attentuation of hundreds of streams of moltenglass and to strandsformed when such continuous glass fiber filamentsare gathered together in forming; and to yarns and cords formed byplying and/or twisting a number of strands together, and to wovenandnonwoven fabrics which are formed of such glass fiber strands, yarnsor cords, and (2) discontinuous fibers fonned by high pressure steam ofair directed angularly downwardly onto multiple streams of molten glassissuing from thebottom side of a glass melting bushing and to yarns thatareformed when such discontinuous fibers are allowed to rain downgravitationally onto a foraminous surface wherein the fibers aregathered together to form a silver .which is drafted into a yarn; and towoven and non-woven fabrics formed of such yarns of discontinuousfibers, and (3) combinations of such continuous and discontinuous fibersin strand, yarn, cord and fabrics formed thereof.

As used herein, the term elastomer is meant to include natural rubber inthe cured or uncured stage, vulcanized or unvulcanized stage, andsynthetic organic elastomeric materials such as butadiene-styrenecopolymer, butadieneacrylonitrile copolymer, chloroprene, isoprene,neoprene,

isobutyl rubber and the like, elastomeric polymers and copolymers intheir cured or uncured stages, and'vulcanized or unvulcanized stages.Included also are the EPDM rubbers, such as formed by theinterpolymerization of ethylene, an alpha-monoolefin having from threeto 20 carbon atoms, such as propylene, and a polyene, such asdicyclopentadiene, 1-4 hexadiene and preferably an alkylene oralkylidene norbornene, such as 5-alkylidene-Z-norbornene and the like inwhich the alkylidene group numbers from two to 12 carbon atoms, andpolysulfone rubber.

The invention is addressed to the fuller utilization of the desirablecharacteristics of glass fibers, such as their high strength,flexibility, thermal stability, chemical stability, inertness,electrical resistance and heat conductive characteristics when used incombinations with elastomeric materials as a reinforcement or as astabilizing agent in belt manufacture, as reinforcing cords and fabricsto increase strength, life, wearability, and service characteristics inrubber tires, and as a reinforcement and the like in other elastomericcoated fabrics and molded elastomeric products.

It is an object of this invention to provide a new and improved methodfor treatment of glass fibers in the form of yarns, cords, strands andfabrics, hereinafter referred to as bundles, wherein the individualglass fibers may or may not contain a thin size coating thereon, toenable fuller utilization to be made of the desirable characteristics ofthe glass fibers when used in combination with elastomeric materials inthe manufacture of glass fiber reinforced molded products and coatedfabrics.

More specifically, it is an object of this invention to provide a methodfor the treatment of glass fibers to improve the processing and theperformance characteristics of the glass fibers as a reinforcement forelastomeric materials and for treatment of bundles, strands, yarns,cords and fabrics of. glass fibers, to enhance their bondingrelationship when used in combination with elastomeric materials in themanufacture of glass fiber reinforced plastics, laminates or coatedfabrics and it is a related object to provide a method and means formaking fuller utilization of the strength properties of glass fiberswhen used as a reinforcement for elastomeric materials.

These and other objects and advantages of this invention willhereinafterappear and, for purposes of illustration, but not oflimitation, an embodiment of the invention is shown in the accompanyingdrawing in which FIG. 1 isa flow diagram. showing the manufacture ofcontinuous glass fibers and the treatment thereof in forming toimprovethe processing characteristicsof the glass fibers and to improve theperformance characteristics of the glass fibers when used in combinationwith elastomeric materials in the manufacture of glass fiber reinforcedelastomeric products;

FIG. 2 is a flow diagram illustrating the treatment of glass fiberssubsequent to their being formed into bundles, strands, yarns, cords orfabrics to impregnate the glass fiber bundles in accordance with thepreferred practice of this invention;

FIG. 3 is a cross-sectional view of glass fibers processed in accordancewith the diagram illustrated in H6. 1; and

FIG. 4-is a cross-sectional view of a bundle of glass fibers processedin accordance with the flow diagram of FIG. 2.

To the present, glass fibers which have been added or otherwiseincorporated with elastomeric materials, in the fonn of continuous orchopped fibers, have functioned more or less as a filler than as areinforcement, or flexibilizing agent, or stabilizing agent. As aresult, little, if any, improvements in mechanical and physicalproperties have been made available from the combinations which made useof glass fibers in products formed or elastomeric materials. It isbelieved that the failure to make fuller utilization of some of the moredesirable properties of the glass fiber components resides in theinability properly to integrate the glass fibers with the elastomericsystem. I

Investigations have been conducted over the past several years by themost highly skilled in the art in the attempt to make fuller utilizationof the glass fiber components formulated into elastomeric materials inthe endeavor to fabricate products having new and improved physical andmechanical properties. Substantial inroads are now being made asrepresented by the practice of this invention, as will hereinafter bedescribed.

In copending application, Ser. No. 398,305, filed Sept. 22, 1964,description is made of'a method for, impregnating glass fibers in theform of yarns, strands, cords or fabrics wherein theglass fiberbundleis. impregnated with a resorcinol aldehyde latex which penetrates theglass fiber bundle to separate the fibers one from the other and toprevent destruction of the fibers by mutualabrasion. When theimpregnated glass fiber bundle is combined with elastomeric materials inthe manufacture of glass fiber-reinforced elastomeric products, theresorcinol aldehyde latex operates to intertie the glass fiber bundlewith the elastomeric material.

The resorcinol aldehyde latex system, hereinafter referred to as RFL hasthe disadvantage that the amount of RFL loaded in the glass fiber bundleas an impregnant is limited by the tendency of the RFL impregnant to bedislodged when the glass fiber bundle is subjected to a change indirection, as when the bundle is passed over the roller or the like. Inaddition, the RFL system as applied in the aforementioned copendingapplication has the further disadvantage that it results in a highdegree of variation in the tensile strength of the glass fiber bundlewhen under compressive forces.

It has now been found that the tensile strength of glass fibers can beunexpectedly increased by treating glass fibers in the form of a bundlewith an elastomer or an elastomer compatible resin prior to impregnationwith RFL, or other similar elastomer compatible impregnant whereby aglass fiber bundle having more than one coating and having improvedcharacteristics for use in the manufacture of glass fiber-reinforcedelastomeric products is produced.

The following examples will serve to illustrate the principal conceptsof this invention in a method for the treatment by impregnation of glassfiber bundles wherein the glass fibers have preferably, though notnecessarily, been sized in forming with a conventional sizecornpositionwhich has preferably been modified to embody a glass fiber anchoringagent.

EXAMPLE 1 Forming Size Composition 8.0% by weight partially dextrinizedstarch 1.8% by weight hydrogenated vegetable oil 0.4% by weight cationicwetting agent(lauryl amine acetate) 0.2% by weight nonionic emulsifyingagent 1.0% by weight gamma aminopropyltriethoxy silane 99.6% by weightwater EXAMPLE 2 Forming Size Composition 3.2% by weight saturatedpolyester resin 0.1% by weight fatty acid amine wetting agent(Nopcogen16 L) 0. l by weight polyvinyl alcohol 3.0% by weight pyrrolidine 0.3%byweight gamma-aminopropyltriethoxy silane 0.1% by weight glacial aceticacid 93.2% by weight water EXAMPLE 3 Forming Size Composition 0.2% byweight paraffin wax in aqueous emulsion 1.3% by weight cationic amidepolyester resin 2.3% by weight polyglycol condensate(300 to 400 m w0.25% by weight gelatin 0.5% by weight gamma-aminopropyltriethoxy silane0.1% by weight dibasic ammonium phosphate 0.2% by weight glacial aceticacid 95.15% by weight water EXAMPLE 4 Forming Size Composition 0.5% byweight beta-aminoethyl-gamma-aminopropyltriethoxy silane 0.25% by weightfatty acid amine wetting agent 99.25% by weight water Referring now tothe schematic diagram of FIG. 1, the glass is melted in a glass meltingfurnace having a bushing 12 on the bottom side. The bushing is formedwith a plurality of openings extending therethrough and the molten glassflows gravitationally through the hundreds of small openings in thebushing to form therein streams 14 which are rapidly attenuated intofine glass filaments 16 by winding the filaments about a rapidlyrotating drum 20. The filaments 16 are sized with one of the sizecompositions of Examples 1 to 3 as they are gathered together to form astrand. For this purpose, use is made of an applicator 22 which isillustrated as a wiping pad that is constantly wet with the forming sizecomposition. The filaments of glass are each wet with the sizecomposition as they are gathered together to form the strand 18 that iswound about the drum 20.

The sized strands are allowed to air dry so drying of the thin sizecoating can be accelerated by exposure to elevated temperature such as atemperature within the range of 150 to 250 F. The applied size forms avery thin coating 24 on the surface of the glass fibers 16 to impart adesired balance of lubricity and bonding without destroying the fibrouscharacteristic or appearance of the fiber.

The strand 18 of sized glass fibers is preferably plied with otherstrands and twisted to form yarns, threads, or cords which may be usedas a reinforcement for elastomeric materials, with or without cutting toshorten lengths, and which can be formed into woven or non-woven fabricsfor subsequent combination with elastomeric materials.

After the fibers have been processed into strands, yarns, cords orfabrics, hereinafter referred to generally as bundles, the bundles ofsized glass fibers are treated in accordance with the process of thepresent invention as represented by the following examples.

EXAMPLE 5 A first impregnating composition is formulated as follows:

25.0% by wt. Natural rubber latex (40% solids) 75.0% by wt. Water.

impregnation with the aqueous composition of Example 5 may be made byconventional means, such as by immersion of the bundles of glass fibersin a bath of the impregnating composition. Referring specifically toFIG. 2 of the drawing, the glass fiber bundle 32 is advanced over aguide roller 34 for passage downwardly to the bath 35 containing theimpregnating composition of Example 5. The bundle is then turned underroller 36 to effect a sharp bend which operates to open the bundle toenable fuller penetration of the aqueous impregnating composition intothe bundle of sized glass fiber for fuller impregnation of the bundle.The impregnated bundle is then raised from the bath for passage througha roller or die 38 which operates to remove excess impregnatingcomposition from the bundle and to work the impregnant into the bundle.

Thereafter, the endless bundle is advanced over roller 40 to roller 42for passage downwardly into a bath 45 containing the followingcomposition:

30.0% by weight natural rubber latex-resorcinol formaldehyde resin (38%solids) Lotol 5440" 70.0% by weight water The bundle is turned underrollers 44 and is passed through orifice die 43 which is somewhatsmaller than die 38 whereby the passage of said strand 32 through die 43causes turbulence in the orifice, aswell as turbulence immediatelybefore and after the orifice, so that a layer comprising a mixture of RFL and natural rubber latex is deposited on the glass fiber bundle 32.The bundle is then passed through the remainder of the RFL bath wherebyRFL is deposited on the top of the binary layer to form a third layercomprising RFL, the excess of which may be removed by an orifice die 46having a somewhat larger diameter. Thereafter, the bundle is advancedover roller 48 into a drying oven preferably in the form of an airdrying oven maintained at a temperature above ambient temperature, andpreferably at a temperature within the range of to 350 F. to accelerateremoval of the aqueous composition and to set the impregnating materialin situ in the glass fiber bundle. However, drying will occur in arelatively short period, ranging from l-30 minutes, depending somewhatupon the temperature of the drying oven. It will be understood that thebundle can be subjected to dielectric treatment to coagulate the latex,thereby effecting little or no drying.

It will be appreciated that limited benefits may be obtained through theuse of the concepts of the present invention wherein die 43 is omittedfrom treating bath 45. In this embodiment, as will be appreciated, theglass fiber bundle will contain an inner coating in the form of anelastomer impregnant and an outer coating in the form of the elastomercompatible material.

The resulting bundle is shown in FIG. 4 and comprises an inner layer 50of natural rubber in which the glass fibers 16 having size coating 24are dispersed, an intermediate layer 52 on top of layer 50 comprising abinary mixture of RFL and natural rubber and an outer layer 54comprising the RFL. However, it will be understood that glass fibers maybe subjected to the treatment described in Example 4 without havingfirst been treated with a sizing composition.

Suitable resorcinol fonnaldehyde resins and combinations thereof withnatural rubber latex are marketed by the U.S.Rubber Company under thetradename of Lotol 5440. For the preparation of same, reference can bemade of Canadian Patent No. 435,754, wherein description is made of thereaction of resorcinol and formaldehyde in the presence of a substantialamount of short-chained alkyl amines for the purpose of stabilizing thereaction and the products formed thereof, as well as the combination ofthe formed resin with rubber latex.

By way of modification, it is possible, and sometimes desirable toinclude in the elastomer latex impregnating composition one or morevulcanizing agents to vulcanize the latex during drying. For thispurpose, use can be made of conventional vulcanizing agents such assulfur, monochloride, selenium, tellurium, thiuram disulfides,polysulfide polymers, zinc oxide, magnesium oxide, organic peroxides aswell as a variety of others. The vulcanizing agent can be employed inamounts up to about 15 percent by weight of the latex.

It will be appreciated that other elastomers may be employed in place ofthe natural rubber shown in Example 5, as

represented by the following example.

EXAMPLE 6 20.0% by wt. Butadiene-styrene copolymer latex(407z solids)80.0% by wt. Water Application to glass fibers which do not contain asize coating thereon is made in the same manner as set forth aboveinExample and in an amount to deposit dry solids comprising l-lO percentby weight of the glass fibers. Subsequent treatment with RFL is made inthe same manner as shown in Example 5 in an amount such that the RF Lconstitutes 2-15 percent by weight of the glass fiber-elastomer system.It will be appreciated that the amount of RFL present in the binaryintermediate layer may be effectively controlled by means of the size ofthe orifice or die 43, and the amount of RF L constituting the outerlayer may be effectively regulated by controlling the amount of RFLsolids present in bath 45 and the size of the orifice or die 46.lmpregnant compositions of the elastomer and RFL generally contain 5-25percent solids by weight.

In accordance with another concept of the present invention, RFL may bereplaced by another elastomer compatible impregnating composition suchas one of the type described in U.S. Pat. No. 3,424,608, as illustratedby the following example.

EXAMPLE 7 20.0% by wt. Neoprene rubber latex (507: solids) 78.0% by wt.Water l.07c by wt. Sulfur 1.0% by wt. Zinc oxide Application of theneoprene latex is made in the manner described in Example 5. While thebundle is still wet with the neoprene latex, the bundle is passed intobath 45 which contains the following elastomer compatible composition.

Parts weight Resorcinol formaldehyde resin 2-10 Formaldehyde (37%solution) 1.3 Concentrated ammonium hydroxide 2-5 Vinyl pyridineterpolymer (42% solids) 15-50 Neoprene rubber latex (50% solids) 25-50Butadiene latex (60% solids) 5-l5 Alkali metal hydroxide 0.05-0.2

Water is incorporated into the foregoing materials in amounts to producean impregnating composition having a minimum solids content of 10percent by weight and a maximum solids content of 50 percent by weight.Application is made in the manner illustrated in FIG. 2.

The vinyl pyridine terpolymer is a terpolymer of about parts pyridine,70 parts butadiene and 15 parts styrene, and is more fully described inthe aforementioned patent. However, it will be understood that the vinylpyridine terpolymer may be used alone to provide the elastomercompatible component in the glass fiber bundle. This concept of thepresent invention is illustrated by the following example.

EXAMPLE 8 Glass fibers impregnated with the neoprene rubber latex ofExample 7 are, while still wet with the neoprene latex, passed into bath45 which contains the following composition.

25.0% by wt. Vinyl pyridine-butadienestyrenc terpolymer (42; solids)75.0% by wt. Water Application of this impregnant to provide a triplecoated glass fiber bundle may be made in the manner described in Example5 which reference to the RFL system.

In accordance with a further concept of the invention, the elastomercomprising the inner layer of the coating may be replaced by a resinouspolymer as illustrated by the following examples.

EXAMPLE 9 25.0% by wt. Polyamide (Nylon) (50% solids) 75.0% by wt. WaterApplication of this composition is made in the same manner as shown inExample 5 whereby the polyamide forms the inner layer of the sized glassfibers. While still wet with the polyamide impregnant, the bundle ispassed to an RF L bath having an orifice die immersed therein to causeturbulence in the vicinity of the die so as to form a triple coatedbundle with a polyamide-RFL binary mixture forming the intermediatelayer and RFL forming the outer layer.

If desired, alcohol solutions of the polyamides may be used instead ofwater suspensoids. It will also be understood that various otherresinous polymers may be used in place of the polyamide, such aspolyester, e.g. those formed by the reaction of a polybasic acid such asphthalic anhydride, maleic acid, furmaric acid and the like with apolyhydric alcohol such as glycerin, glycol and the like,phenolic-aldehydes such as phenol-formaldehyde resins, polyepoxides andacrylics.

It is desirable to achieve as full impregnation as possible into thebundles of glass fibers in order to more effectively separate the fibersone from the other by the impregnating materials since the solids areeffective as a coating on the sized glass fibers to cushion the fibersand to protect the fibers against destruction by mutual abrasion. Thus,it is desirable to achieve as deep penetration as possible with theimpregnating composition into the glass fiber bundle. The deeper thepenetration, the more effective will be the bond between the glassfibers in the bundle and the elastomeric material with which the bundlesof glass fibers are combined in the subsequent manufacture of the glassfiber-elastomeric product.

In the final system, the elastomeric material with which the glassfibers are combined will constitute a continuous phase. Such continuousphase of elastomeric material may comprise rubbers of the typeincorporated into the impregnating composition or the elastomericmaterial can differ therefrom. The continuous phase of elastomericmaterial can be employed in the cured or uncured state or in thevulcanized or unvulcanized state. It is believed that the tie-in betweenthe impregnated bundles of glass fibers and the elastomeric materialforming the continuous phase will occur primarily during cure orvulcanization of the elastomeric material during the fabrication of theelastomeric material.

More complete protection of the individual glass fibers and a fullercoordination with the elastomeric material can be achieved when eitherthe first or second or both of the impregnating compositions areformulated to contain an anchoring agent such asgamma-aminopropyltriethoxy silane. Instead of gamma-aminopropyltriethoxysilane, in the size or in the impregnating composition, use can be madeof other organo silicon compounds containing an amino group, such asgamma-aminovinyldiethoxy silane,gamma-(triethoxysilylpropylamide)propylamine,N(gamma-triethoxysilylpropyl)propylamine, beta-aminoallyltriethoxysilane, and

para-aminophenyltriethoxy silane. Use can be made of other organosilicon compounds in the form of a silane, silanol or polysiloxanepolymers and copolymers(e.g. amino silane-organo silane copolymers) inwhich the organic group attached to the silicon atom contains an epoxygroup, such as glycydoxypropyltrimethoxy silane or3,4-epoxycyclohexylethyltrimethoxy silane. Instead of the organo siliconcompounds, use can be made of a Werner complex compound in which thecarboxylato group coordinated with the trivalent nuclear chromium atomcontains an amino group or an epoxy group such as aminopropylato chromicchloride, glycine chromic complex, B-alanine chromic complex, orglycylate chromic chloride.

This concept of the present may be illustrated by the followingexamples.

EXAMPLE 10 30.0% Natural rubber latex(50% solids) 1.0%Gamma-aminopropyltriethoxy silane 69.0% Water The foregoing compositionmay be applied to a glass fiber bundle in which the individual glassfibers retain their original size. While the'fibers are still wet withthe latex, the bundle is treated with RFL which may or may not containan anchoring agent.

EXAMPLE 11 An RF L composition containing an anchoring agent may beformulated as follows:

25.0% RFL 1.5% Anchoring agent 73.59: Water When employing an anchoringagent in the impregnating compositions as illustrated by Examples 9 and10, it is frequently advantageous to include a quaternary aminocompound, such as tetramethyl ammonium hydroxide or tetra ethanolammonium hydroxide, in order to impart improved stability to theimpregnating compositions and to aid in maintaining the anchoringagent'in solution.

' ln fabricating the combinations of the glass fibers treated inaccordance with the practice of this invention, with elastomericmaterials, the glass fibers or bundles of glass fibers are mixed withelastomeric material or otherwise laid down in the desired arrangementfor combination with the elastomeric material as in the manufacture ofrubber tires reinforced with cords of glass fibers. The combination ofglass fibers and elastomeric material is processed in a conventionalmanner by molding or cure under heat and compression or by vulcanizationfor advancement of the elastomeric material to a cured or vulcanizedstage while in combination with the treated glass fibers whereby theglass fibers or bundles of glass fibers become strongly integrated withthe elastomeric material in the glass fiber elastomeric product.

It will be apparent that l have provided a new and improved method foruse in the treatment of bundles of glass fibers to enhance theirintegration with elastomeric materials in the manufacture of glassfiber-elastomeric products.

It will be understood that invention exists not only inthe treated glassfibers for use with elastomeric materials but that invention exists alsoin the process in which the compositions are employed in the treatmentof glass fibers as well as the treated or impregnated glass fiberproducts formed thereof.

It will be understood that changes may be made in the details offormulation and methods of application for use without departing fromthe spirit of the invention, especially as defined in the followingclaims.

lclaim: g

"I. in the manufacture of glass fiber-elastomeric products in which theelastomeric material comprises a continuous phase in'which the glassfibers are distributed, the treatment of glass resins and acrylic resinsto form an inner layer impregnant of said polymeric material in saidglass fiber bundle, passing the glass fiber bundle which is stillwetwith said first composition into a bath of an elastomer compatiblematerial, said bath having immersed therein an orifice through whichsaid bundle is passed whereby turbulence is created in the vicinity ofthe orifice to intermix the elastomer compatible material with thepolymeric material to provide an intermediate impregnant layercomprising a mixture of said polymeric material with an elastomercompatible material, and further coating the resulting bundle with anelastomer compatible material to form a top coating on said glass fiberbundle of said elastomer compatible material, said elastomer compatiblematerial being selected from the group consisting of resorcinol aldehydelatex and a vinyl pyridine-butadiene-styrene terpolymer.

2. A method as defined in claim 1 wherein said inner layer impregnantconstitutes l-l0 percent by weight of said glass fiber.

3. A method as defined in claim 1 wherein the top coating constitutes2-15 percent by weight of the glass fiber-inner layer system.

4. A method as defined in claim 1 wherein at least one of saidcompositions contains an anchoring agent.

5. A glass fiber bundle having three impregnant layers therein, thefirst of said impregnant layers comprising a polymeric material selectedfrom the group consisting of an elastomer and a resinous polymerselected from the group consisting of polyamides, polyesters,polyepoxides, phenolic aldehyde resins and acrylic resins, the secondimpregnant layer comprising a mixture of said polymeric material and anelastomer compatible material selected from the group consisting of aresorcinol aldehyde latex and a vinyl pyridine-butadiene-styreneterpolymer and the third impregnant layer comprising a top coating inthe form of said elastomer compatible material.

6. A glass fiber bundle as defined in claim 5 wherein said inner coatingconstitutes 1-l0 percent by weight of said glass fiber.

7. A glass fiber bundle as defined in claim 5 wherein said outer coatingconstitutes 2-l5 percent by weight of the glass fiber-innerlayer system.

8. A glass'fiber bundle as defined in claim 5 wherein at least one ofsaid polymeric material and said elastomer compatible material includesan anchoring agent.

9. In the manufacture of glass fiber elastomeric products in which theelastomeric material comprises a continuous phase in which the glassfibers are distributed, the treatment of glass fibers which is effectiveto establish a strong bonding relationship between the glass fibers andthe continuous phase elastomeric material comprising impregnating aglass fiber bundle with a first composition comprising a polymericmaterial selected from the group consisting of polyamides, polyesters,polyepoxides, phenolic aldehyde resins and acrylic resins to form aninner layer impregnant of said polymeric material in said glass fiberbundle, passing the glass fiber bundle which is still wet with saidfirst composition into a bath of an elastomer compatible material, saidbath having immersed therein an orifice through which said bundle ispassed whereby turbulence is created in the vicinity of the orifice tointermix the elastomer compatible material with the polymeric materialto provide an intermediate impregnant layer comprising a-mixture of saidpolymeric material with an elastomer compatible material, and furthercoating the resulting bundle with an elastomer compatible material toform a top coating on said glass fiber bundle of said elastomercompatible material, said elastomer compatible material being selectedfrom the prising a mixture of said polymeric material and an elastomercompatible material selected from the group consisting of resorcinolaldehyde latex and a vinyl pyridine-butadienestyrene terpolymer and thethird impregnant layer comprising a top coating in the form of saidelastomer compatible materia].

2. A method as defined in claim 1 wherein said inner layer impregnantconstitutes 1-10 percent by weight of said glass fiber.
 3. A method asdefined in claim 1 wherein the top coating constitutes 2-15 percent byweight of the glass fiber-inner layer system.
 4. A method as defined inclaim 1 wherein at least one of said compositions contains an anchoringagent.
 5. A glass fiber bundle having three impregnant layers therein,the first of said impregnant layers comprising a polymeric materialselected from the group consisting of an elastomer and a resinouspolymer selected from the group consisting of polyamides, polyesters,polyepoxides, phenolic aldehyde resins and acrylic resins, the secondimpregnant layer comprising a mixture of said polymeric material and anelastomer compatible material selected from the group consisting of aresorcinol aldehyde latex and a vinyl pyridine-butadiene-styreneterpolymer and the third impregnant layer comprising a top coating inthe form of said elastomer compatible material.
 6. A glass fiber bundleas defined in claim 5 wherein said inner coating constitutes 1-10percent by weight of said glass fiber.
 7. A glass fiber bundle asdefined in claim 5 wherein said outer coating constitutes 2-15 percentby weight of the glass fiber-inner layer system.
 8. A glass fiber bundleas defined in claim 5 wherein at least one of said polymeric materialand said elastomer compatible material includes an anchoring agent. 9.In the manufacture of glass fiber elastomeric products in which theelastomeric material comprises a continuous phase in which the glassfibers are distributed, the treatment of glass fibers which is effectiveto establish a strong bonding relationship between the glass fibers andthe continuous phase elastomeric material comprising impregnating aglass fiber bundle with a first composition comprising a polymericmaterial selected from the group consisting of polyamides, polyesters,polyepoxides, phenolic aldehyde resins and acrylic resins to form aninner layer impregnant of said polymeric material in said glass fiberbundle, passing the glass fiber bundle which is still wet with saidfirst composition into a bath of an elastomer compatible material, saidbath having immersed therein an orifice through which said bundle ispassed whereby turbulence is created in the vicinity of the orifice tointermix the elastomer compatible material with the polymeric materialto provide an intermediate impregnant layer comprising a mixture of saidpolymeric material with an elastomer compatible mAterial, and furthercoating the resulting bundle with an elastomer compatible material toform a top coating on said glass fiber bundle of said elastomercompatible material, said elastomer compatible material being selectedfrom the group consisting of resorcinol aldehyde latex and a vinylpyridine-butadiene-styrene terpolymer.
 10. A glass fiber bundle havingthree impregnant layers therein, the first of said impregnant layerscomprising a polymeric material selected from the group consisting ofpolyamides, polyesters, polyepoxides, phenolic aldehyde resins andacrylic resins, the second impregnant layer comprising a mixture of saidpolymeric material and an elastomer compatible material selected fromthe group consisting of resorcinol aldehyde latex and a vinylpyridine-butadiene-styrene terpolymer and the third impregnant layercomprising a top coating in the form of said elastomer compatiblematerial.